The present invention relates to a method for forming perforations on a printed circuit board consisting of a mother portion and supplementary portions to be separated from the mother portion.
When manufacturing printed circuit boards, perforations are formed on the board to make possible the separation of the supplementary portions from the mother portion.
In this case, the usual perforation process is to simultaneously punch a plurality of through holes along a line. This process often causes a serious strain along the line, the magnitude and orientation of which depends on the arrangement of the holes. This strain leads to the formation of cracks which renders the product defective and unacceptable.
There is a known method for manufacturing printed circuit boards that prevents such defects. Such a conventional method is disclosed, for example, in Japanese Patent No. H1-49031. The method employs a technique in which a metal mold punch is used to form waste holes in a neighboring supplementary portion at the same time that perforations are formed, thus preventing the neighboring supplementary portion from moving outwards, which in turn prevents the formation of cracks along the perforations or a premature separation of the supplementary portion.
However, the above conventional method requires that the structure of the conventional metal mold for press-working a printed circuit board be modified significantly in order to introduce such extra punches onto the structure. In addition, this increases the stress on the entire mold, thereby shortening the life of the mold.